Smallpox: anything to declare?

Smallpox was eradicated in 1977, but it remains a concern owing to the potential use of the causative agent variola virus in bioterrorism. This article provides an overview of the World Health Organization's spectacular success in achieving the eradication of smallpox. It discusses how variola virus could potentially re-emerge and how prepared we are to counter such a re-emergence. Finally, the potential threat from other orthopoxviruses that exist naturally or that have been genetically engineered is considered. In the words of Rep. Christopher Shay, 'Better to be scared by the improbable possibility than to be unprepared for the catastrophic reality'.